Process of making steel and iron.



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To all whom it may concern Be it known that l, Sunawoon S. KNIG T, acitizen of the United States, residingat Berkeley, in. the county ofAlameda and State of California, have invented new and usefulImprovements in Processes of t ials ing Steel and Iron, of which thefollowing is a specification. 1

My invention is a method of making iron and steel of very high gradesWholly or largely from cheap; inferior, cold raw ma terial.

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While I ordinarily use a basic, openliearth furnace in this process,under certain. conditions any basic regenerative furnace or electricalfurnace oi either induction or resistance types, or combinations oithese, may be used.

Inasmuch as the successive elimination of the impurities includingcarbon in steel tends to cause the product to approximate pure iron,.theexact point Where the material ceases to be steel and becomes iron isundefined and apparently undeiinable.

My invention has to do with the produc tion of both steel and iron ;-thefinal product depending upon the point to which elimination of elementsother thaniron has been carried, or the amount of elements other than.iron added to produce the desired grade of steel.

Various attempts have been made to make high grade iron and steelWithout theuse of pig iron, cast iron or other iron products high incarbon, such as cemcntation steel and the like. In making this class ofproducts at the present time out of cold stock by other methods, "from50% to of pig iron or cast iron is usually required, while by my processunder ideal conditions, no such material required, whereas under averageconditions but 1 orless would be required, and in no case would over 20%be required. It Will be understood that light barometric pressure,increased percentages of aqueous vapor in the air, variation in theoperation of the furnace, (due to detective draft, bad furnace lines andthe like), all tend to require the use of pig iron or cast iron, andconstitute variations from ideal. operating conditions.

By my. process, the highest grades oi" Specifics tion of Letters Eatent.Pg tgm tg gqll Jlam;23l M1911? Application flied February 1914. SerialNo. hit/lee.

depends upon the relative availability of the various grades of rawmaterial ll use in manutacturing' under this process in the place whereand at the time when the process is used.

There is another important advantage in the use of my process over allexisting methods, namely: the time consumed in the manufacture isgreatly reduced, running from 15% to 50%, according as conditions aremore or less favorable. This is because the percentage of carbon in pigiron and cast iron is much greater than in the nuaterials I use.

All grades of iron and steel are and have for many years been made byprocesses ordinarily knownto the trade as the puddling process or theingot process. Some oi the iron heretofore manufactured by the pu'd-(llinp; process is as pure as that nianufac tured by the ingot processand has-the same genera characteristics even in a more marked. degree;but all puddled irdn contains a small percentage of'slag. Ali ingot ironand steelis slagless if properly-made. The product of my improvedprocess of manufacture is slagless although otherwise having the samecrystalline mass if made by the puddling process. Y

ay my process, the cost of thehigh grade finished product will begreatly reduced for the reasons above stated; and will thereforeli'orniing material introduced to effect the elimination of phosphorusand sulfur built up on the bottom Off the furnace, soreducing theholding capaclty of the furnace as to render its operation unprofitable,and leak ing it impracticable toget this mass out of the furnace; forwhen acid material was used for the purpose, the films ce bottom Wasbadly damaged and expensive repairs were required; (2) the carhonizing:material was charged in such a Way that fuel, coining in contact with itat high velocity'antl heat, carried it out of contact with the metal ofthe bath before a suiiicient carbonizing of the bath. could take place.This carhonizing 'rneteriil' was carried over into the slagthe pocketsand regenerating chambers of furnace and in a short time would socumulate as to seriously interfere with the draft of the furnace, makingfrequent expensive overhauling and repairs necessary. In my process themanner of charging ob \iates both these dilficultics.

My process consists in charging in the manner now to be described abasic openhearth furnace using oil, producer gas, tar or other fuel,after the furnace has been brought up to charging heat, the bottomhaving previously been put in good cont ition, all holes being patchedand the filling set. (1) 1 first charge low carbon steel scrap of smallsection, or wrought iron-scrap such as wind steel-plate shearings,bundled sheetscrap or material of a like kind, or borings and turningsof steel regardless of their carbon content, directly onto the bottom ofthe furnace so as to completely cover it. The object of this step is toplace a layer of ferrous material between the basic material of thebottom of the furnace and the basic material used for reducing thesulfur and phosphorus content of the charge in the process as hereafterdescribed. If this is not done, the basic material which is added forthe reduction of the sulfur and phosphorus content will build onto thebottom of the furnace and very materially interfere with the economicaloperation of (the furnace. This layer is then so heated as to reduce itto a pasty mass, which mass forms a shield and protection to the basicmaterial of the bottom against the basic material subsequently charged.1; relatively small quantity of oXid of iron in suitable form such asiron ore or rolling mill scale may be charged directly onto the firstlayer of ferrous material above described for the purpose of coun-. theferrous.

excess carbon in facilitate the rapid operation of the process. If thematerial of the ferrous layer is low in carbon or is mild steel, theaddition of iron oxid will be unnecessary. T he first ferrous layershould constitute 01- dinarily about from 10% to 20% of the entirecharge by weight. (2) When this first ferrous layer has begun to softenup or partially melt or become pasty, I charge burned lime or limestone,(the latter being preferred), on top of the ferrous layer. The amount oflimestone used depends upon the amount of elements other than iron, suchas phosphorus and sulfur in the ferrous mateterial used and willusually'run from 5% to 20% of the total charge according to the purityof the limestone and the impurity of the ferrous material in the bath.(3) Directly on top of this limestone layer,

charge steel-scrap and an-bon-niaterial such as retort-carbon, screenedcoke braize or anthracite coal screenings. If this second ferrous layeris charged in charging boxes,

tel-acting any layer and thus 'bath of the required quality the boxesshould be filled about four inches from the top with the steel-scrap andon top of this should be thrown the carbonaceous material so that whenthe charging boxes are inverted in dumping into the furnace, thesteel-scrap will, as nearly. as possible, cover up the carbonaceousmaterial. which will fall first upon the limestone and thus prevent itbeing forced into the slag pockets and regenerating chambers of thefurnace by the draft. If the furnace is hand-charged, the fuel will haveto be shut oil and the draft discontinued while the car bonaceousmaterial is being SllUYtlCd into the furl'iace onto the limestone andnot turned on again with force until a suliicientquantity of steel scraptop of it to protect it from the tional. charges of steel scrap ceousmaterial are entire charge is finished. is then driven at as high atemperature as practicable, for the higher the temperature attained, themore rapi lly the ferrous material will melt and consequently, thegreater the saving in time in making the heat. The charge will normallymeltdown so that when the melting operation is finished, the carboncontent of the bath will run from 50% to .9070. Ifit is found that thematerial does not melt high enough in carbon, a small amount of pig ironor cast iron scrap can be added to increase the carbon content to thedegree preferred to make the operation of the furnace rapid. andsuccessful. It is preferable, of course, to charge such steel scrap asruns high in carbon. lrleavy melting steel or scrapsteel rails usuallycarry from 20% to .JJif/a carbon. After the ferrous material is melted,ore is then added sparingly, agitation of the bath is resorted to.o'rthe continued application of heat may be used until the material ishrmi'ght down. to such a carbon content as is required in the finishedproduct. If a ferrous product almost free from elements other than ironis required, the material is left longer in the furnace, with or withoutadditions to the slag of powdered burned lime or fluorspar or both,until the bath shows such analysis and such freedom from elements otherthan iron as is necessary to produce a product of the prescribed grade.When a is obtained, the furnace is tapped in the usual way into a ladle.The cinder or slag is allowed to run off in the usual manner and in caseany difiiculty should be encountered by the phosphorus in the slagattempting to go back into the metal in the ladle, the addition of asmall amount of powdered burned lime just before the ladle leaves thefurnace and after the slag has run oil? as much as it will, effectuallyprevents this.

Material can be produced under the above has been placed on draft.Addiand carbonaadded as needed until the (a) The furnace describedprocess of almost any desired degree of purity, sulfur being the onlyelement which cannot be completely eliminated,-it usually running 015%or over. Assuming thatyby this process a product- .has beenproducedhaving of silicon a trace, of manganese a trace, of sulfur 020%, ofphosphorus a trace, and steel castlngs or practice in steel manufacturefor many years.

The steel or nearly pure iron base resulting from the manu' acture undermy above described process is especially suited to the manufacture ofalloyed steels. The alloy -may be made by uniting with this base thedesired alloying materials, either molten or solid, just before tappingout, or afterward in. the ladle. ;In this manner, very superiorqualities of manganese steel, niclrel-chrome, vanadium, titanium, etc.steel may be read ily produced,the extremely low phosph rus and sulfurcontent of the final prod not of my process enabling such alloys ofbetter quality to be produced than by any other method at present inuse, and at very considerable less cost.

I claim as my invention, and desire to secure by Letters Patent of theUnited States l. The improvement in process of manufactoring iron orsteel in a basic, open hearth furnace, consisting, first, in chargingdirectly onto the bottom a layer of ferrous material low in carbon tothe extent of approximately 10% to i 20% by weight of the entire charge,completely covering the bottom of the furnace; second, heating thisferrous material sufliciently to cause it to become a pasty mass; third,charging non-ferrous material containing free carbon, and subsequentlycharging a fiuxing material and ferrous material; and fourth,

finishing and drawing off the product.

2. The improved process for the manufacture of iron or steel consistingin' first: charging directlyon the bottom of the furnace a completelayer, say 10% to 20% of theentire charge by weight,of ferrous materialcomparatively low in carbon; second: charging directly upon said ferrouslayer, when softened or pasty from heat, burned lime or limestone, about5% to 20% of the entire charge; third: charging upon the limestone layeradditional charges of ferrous material and carbonizing material of anon-ferrous nature com posed largely of free carbon until the entirecharge is completed; fourth, driving the furnace at a sufliciently hightemperature to rapidly liquefy the ferrous material until the bath runsfrom to .90% carbon (with or without addition of highly carbonizedferrous material as ma be necessary to this end); fifth: after theferrous material of the charge is liquefied, reducing the elements.other than iron, and sixth, finishing and drawing off the product.

3. The improvement in the process of manufacturing refined iron or steelin a basic lined furnace, consisting first in charging directly onto thebottom of the Y furnace a layer of ferrous material such as steel orwrought iron scrap or material of a similar nature, in an amountsufficient to cover the bottom of the furnace, and heating said layer toreduce it to a pasty mass and thus forming a shield and protection tothebasic material of the bottom against the basic material subsequentlycharged; then charging the furnace with basic material and ferrousmaterial, and then rapidly reducing the comparative quantity of thematerials other than iron and finishing and drawing off the product.

In testimony whereof I have hereunto set my hand in presence of twosubscribingwitnesses;

SHERWOOD SKNIGHT. Witnesses:

A L. Thinnest, WALTER A. KNIGHT;

